I got my very first betta fish around 3 weeks ago and just yesterday, I decided to upgrade his aquarium to a much bigger one compared to his previous bowl. I got a 17L tank with a filter and light. Even added a thermometer to monitor the temperature.
Before I placed him in his new tank, I treated the water with the following:
1. Aquarium Salt
2. Water conditioner - for chlorine, nitrate and heavy metals
3. Black water
The fish shop told me to go buy this.
It's been a day since I transferred him and just this morning I noticed his head is turning black. I don't know know what's happening. HELP PLEASE.
Adding a photo. Appreciate your advice guys. Is there anything I could do to treat this?